JANUARY, 10 2008: Supermarket giant Sainsbury's has hit back at criticisms that the poultry meat and eggs on sale in its stores are derived from systems which involve animal suffering.

Thousands of letters and leaflets have been sent to its customers across the country this week, stating that it only sources these products from farms demonstrating high levels of animal welfare.

"We take our responsibilities for animal welfare very seriously as we know that, for our customers, it is not only the quality of what we sell that is important, but also how these products are sourced."

All of Sainsbury's chicken and eggs are from British farms, it says, though they are sourced from a range of production systems.

Two accompanying leaflets explain the different labels that appear on their products, with a basic interpretation of what they mean.

For example, Sainsbury's basics eggs are from caged hens, though they all carry the British Lion Quality mark to show they are from quality assured units.